Members of legendary gospel singer Mahalia Jackson’s estate are aghast that 2004 “American Idol” winner Fantasia Barrino has become pregnant by a married man as she prepares to play the Queen of Gospel in the biographical film “Mahalia!”

Producers are also furious with Fantasia, 27, for not telling them about her unexpected pregnancy until she was four months in. “She [initially] claimed that she was putting on weight for the role,” an insider said.

Production of the movie has been pushed back because of Fantasia’s pregnancy with her married boyfriend, Antwaun Cook.

“The family thinks if Fantasia plays the role, it’s going to sully the name of Mahalia,” executive producer Adrian Taylor told us. “They think she’s got the wrong image, having a child out of wedlock.”

Barrino’s pregnancy has also caused chaos with scheduling conflicts because filming has been delayed until after her due date on Dec. 27. Director Euzhan Palcy may be forced to drop out of the project.

Producers are now scrambling to finish the movie by fall 2012. Barrino has been asked to start filming as soon as January and is in negotiations to alter her contract to allow time for breast-feeding and nurturing her child on set.

In the meantime, producers are working to find a replacement if Barrino doesn’t agree to start shooting after New Year’s. Missy Elliott has been suggested.

Because of the unexpected bump, the film’s budget has been increased from $23 million to $27 million.

Dino Gankendorff, who represents Mahalia Jackson’s estate, told us, “I’m not really aware of any objections that the heirs have to the casting of Fantasia. I understand that they were getting ready to film and that she is pregnant, and I don’t know who is she pregnant by.”

Barrino’s rep said, “This is the first time I’ve heard about this. I have no comment.”